From ea725456ee1463cbc7278a81f0ea43046c7b3cea Mon Sep 17 00:00:00 2001
From: Neil Mitchell <ndmitchell@gmail.com>
Date: Fri, 7 Nov 2014 14:50:17 +0000
Subject: [PATCH] #3, make it work on Windows

---
 src/System/Console/Terminal/Size.hs    | 42 ++++++++++++++++----------
 src/System/Console/Terminal/Windows.hs | 41 +++++++++++++++++++++++++
 terminal-size.cabal                    | 11 ++++---
 3 files changed, 73 insertions(+), 21 deletions(-)
 create mode 100644 src/System/Console/Terminal/Windows.hs

diff --git a/src/System/Console/Terminal/Size.hs b/src/System/Console/Terminal/Size.hs
index df40349..aa7173a 100644
--- a/src/System/Console/Terminal/Size.hs
+++ b/src/System/Console/Terminal/Size.hs
@@ -1,21 +1,37 @@
+{-# LANGUAGE CPP #-}
 {- |
 Get terminal window height and width without ncurses dependency
 
-Only tested to work on GNU/Linux systems
-
 Based on answer by Andreas Hammar at <http://stackoverflow.com/a/12807521/972985>
 -}
 module System.Console.Terminal.Size
-  ( Window(..), size, fdSize, hSize
+  ( Window(..), size
+#if !defined(mingw32_HOST_OS)
+    ,fdSize, hSize
+#endif
   ) where
 
 import System.Console.Terminal.Common
-import qualified System.Console.Terminal.Posix as Posix
+#if defined(mingw32_HOST_OS)
+import qualified System.Console.Terminal.Windows as Host
+#else
+import qualified System.Console.Terminal.Posix as Host
 import System.Posix.Types(Fd)
 import System.IO(Handle)
+#endif
+
 
+-- | Get terminal window width and height for @stdout@.
+--
+-- >>> import System.Console.Terminal.Size
+-- >>> size
+-- Just (Window {height = 60, width = 112})
+size :: Integral n => IO (Maybe (Window n))
+size = Host.size
 
--- | Get terminal window width and height for a specified file descriptor. If
+#if !defined(mingw32_HOST_OS)
+-- | /Not available on Windows:/
+-- Get terminal window width and height for a specified file descriptor. If
 -- it's not attached to a terminal then 'Nothing' is returned.
 --
 -- >>> import System.Console.Terminal.Size
@@ -26,21 +42,15 @@ import System.IO(Handle)
 -- >>> fdSize fd
 -- Nothing
 fdSize :: Integral n => Fd -> IO (Maybe (Window n))
-fdSize = Posix.fdSize
-
--- | Get terminal window width and height for @stdout@.
---
--- >>> import System.Console.Terminal.Size
--- >>> size
--- Just (Window {height = 60, width = 112})
-size :: Integral n => IO (Maybe (Window n))
-size = Posix.size
+fdSize = Host.fdSize
 
--- | Same as 'fdSize', but takes 'Handle' instead of 'Fd' (file descriptor).
+-- | /Not available on Windows:/
+--   Same as 'fdSize', but takes 'Handle' instead of 'Fd' (file descriptor).
 --
 -- >>> import System.Console.Terminal.Size
 -- >>> import System.IO
 -- >>> hSize stdout
 -- Just (Window {height = 56, width = 85})
 hSize :: Integral n => Handle -> IO (Maybe (Window n))
-hSize = Posix.hSize
+hSize = Host.hSize
+#endif
diff --git a/src/System/Console/Terminal/Windows.hs b/src/System/Console/Terminal/Windows.hs
new file mode 100644
index 0000000..595cc8b
--- /dev/null
+++ b/src/System/Console/Terminal/Windows.hs
@@ -0,0 +1,41 @@
+
+module System.Console.Terminal.Windows(size) where
+
+import System.Console.Terminal.Common
+
+import Control.Monad
+import Data.Word
+import Foreign.Ptr
+import Foreign.Storable
+import Foreign.Marshal.Alloc
+
+type HANDLE = Ptr ()
+
+data CONSOLE_SCREEN_BUFFER_INFO
+
+sizeCONSOLE_SCREEN_BUFFER_INFO :: Int
+sizeCONSOLE_SCREEN_BUFFER_INFO = 22
+
+posCONSOLE_SCREEN_BUFFER_INFO_srWindow :: Int
+posCONSOLE_SCREEN_BUFFER_INFO_srWindow = 10 -- 4 x Word16 Left,Top,Right,Bottom
+
+c_STD_OUTPUT_HANDLE :: Word32
+c_STD_OUTPUT_HANDLE = -11
+
+foreign import stdcall unsafe "windows.h GetConsoleScreenBufferInfo"
+    c_GetConsoleScreenBufferInfo :: HANDLE -> Ptr CONSOLE_SCREEN_BUFFER_INFO -> IO Bool
+
+foreign import stdcall unsafe "windows.h GetStdHandle"
+    c_GetStdHandle :: Word32 -> IO HANDLE
+
+
+size :: Integral n => IO (Maybe (Window n))
+size = do
+    hdl <- c_GetStdHandle c_STD_OUTPUT_HANDLE
+    allocaBytes sizeCONSOLE_SCREEN_BUFFER_INFO $ \p -> do
+        b <- c_GetConsoleScreenBufferInfo hdl p
+        if not b then return Nothing else do
+            [left,top,right,bottom] <- forM [0..3] $ \i -> do
+                v <- peekByteOff p ((i*2) + posCONSOLE_SCREEN_BUFFER_INFO_srWindow)
+                return $ fromIntegral (v :: Word16)
+            return $ Just $ Window (1+bottom-top) (1+right-left)
diff --git a/terminal-size.cabal b/terminal-size.cabal
index fc06b28..a44b17a 100644
--- a/terminal-size.cabal
+++ b/terminal-size.cabal
@@ -2,9 +2,7 @@ name:                terminal-size
 version:             0.2.1.0
 synopsis:            Get terminal window height and width
 description:
-  Get terminal window height and width without ncurses dependency
-  .
-  Only tested to work on GNU/Linux systems
+  Get terminal window height and width without ncurses dependency.
 license:             BSD3
 license-file:        LICENSE
 author:              Andreas Hammar, Matvey Aksenov
@@ -19,8 +17,11 @@ library
   build-tools:       hsc2hs
   hs-source-dirs:    src
   exposed-modules:   System.Console.Terminal.Size
-  other-modules:     System.Console.Terminal.Posix
-                     System.Console.Terminal.Common
+  other-modules:     System.Console.Terminal.Common
+  if os(Windows)
+    other-modules:   System.Console.Terminal.Windows
+  else
+    other-modules:   System.Console.Terminal.Posix
   ghc-options:       -Wall
                      -fno-warn-unused-do-bind